Congenital deficiency reveals critical role of ISG15 in skin homeostasis
Muhammad Nasir Hayat Malik, … , Thomas Werfel, Frank Pessler
Muhammad Nasir Hayat Malik, … , Thomas Werfel, Frank Pessler
Published November 30, 2021
Citation Information: J Clin Invest. 2022;132(3):e141573. https://doi.org/10.1172/JCI141573.
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Research Article Autoimmunity

Congenital deficiency reveals critical role of ISG15 in skin homeostasis

Abstract

Ulcerating skin lesions are manifestations of human ISG15 deficiency, a type I interferonopathy. However, chronic inflammation may not be their exclusive cause. We describe two siblings with recurrent skin ulcers that healed with scar formation upon corticosteroid treatment. Both had a homozygous nonsense mutation in the ISG15 gene, leading to unstable ISG15 protein lacking the functional domain. We characterized ISG15–/– dermal fibroblasts, HaCaT keratinocytes, and human induced pluripotent stem cell–derived vascular endothelial cells. ISG15-deficient cells exhibited the expected hyperinflammatory phenotype, but also dysregulated expression of molecules critical for connective tissue and epidermis integrity, including reduced collagens and adhesion molecules, but increased matrix metalloproteinases. ISG15–/– fibroblasts exhibited elevated ROS levels and reduced ROS scavenger expression. As opposed to hyperinflammation, defective collagen and integrin synthesis was not rescued by conjugation-deficient ISG15. Cell migration was retarded in ISG15–/– fibroblasts and HaCaT keratinocytes, but normalized under ruxolitinib treatment. Desmosome density was reduced in an ISG15–/– 3D epidermis model. Additionally, there were loose architecture and reduced collagen and desmoglein expression, which could be reversed by treatment with ruxolitinib/doxycycline/TGF-β1. These results reveal critical roles of ISG15 in maintaining cell migration and epidermis and connective tissue homeostasis, whereby the latter likely requires its conjugation to yet unidentified targets.

Authors

Muhammad Nasir Hayat Malik, Syed Fakhar-ul-Hassnain Waqas, Jana Zeitvogel, Jingyuan Cheng, Robert Geffers, Zeinab Abu-Elbaha Gouda, Ahmed Mahrous Elsaman, Ahmed R. Radwan, Matthias Schefzyk, Peter Braubach, Bernd Auber, Ruth Olmer, Mathias Müsken, Lennart M. Roesner, Gisa Gerold, Sven Schuchardt, Sylvia Merkert, Ulrich Martin, Felix Meissner, Thomas Werfel, Frank Pessler

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Figure 12

Retarded cell migration in ISG15–/– HaCaT keratinocytes normalizes under treatment with RUX but not TGF-β1.

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Retarded cell migration in ISG15–/– HaCaT keratinocytes normalizes under...
Scratch assays were performed with WT or ISG15–/– HaCaT keratinocytes, and gap closure was measured by automated image analysis for 30 hours. Images show start (0 hours) and end (30 hours). Images of all time points are shown in Supplemental Figures 15 and 16. The black lines delineate the borders of the scratch. (A–C) TGF-β1 treatment. Treatment delays gap closure similarly to triple treatment (see Supplemental Figure 14). (D–F) RUX treatment. Treatment accelerates gap closure in ISG15–/– cells to a speed similar to that in WT cells. n = 3, ± SEM; *P < 0.05, **P < 0.01, ***P < 0.001 (1-way ANOVA with Tukey’s post hoc test).